1. Technical Field
The present disclosure relates to light ray concentration devices and, particularly, to a light ray concentration devices for solar cells.
2. Description of Related Art
Light rays concentration devices for solar cells generally include a convex lens that focuses light ray on the solar cells. To reduce the distance between the convex lens and the solar cell, the convex lens with a short focal length is preferred. However, the thickness of the convex lens having a short focal length is large, which means that the light ray concentration device is bulky. To solve this problem, Fresnel lenses are employed in the light rays concentration devices instead of the convex lenses. However, a typical Fresnel lens only defines a Fresnel zone on a planar side thereof for concentrating light rays. The focal length of the typical Fresnel lens is not short enough to be satisfactory.
Therefore, it is desirable to provide a new light ray concentration device, which can overcome the above-mentioned limitations.